From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Wez <wez@chromium.org>
Date: Thu, 15 Apr 2021 18:24:27 +0000
Subject: Handle window deletion during HandleDisplayChange.

In principle there is no reason why the HWNDMessageHandler shouldn't be
deleted by a HandleDisplayChange() call out to the delegate, e.g. if the
change results in a change in window layout.

(cherry picked from commit 299155e5e37a77670b7969771e09e9a16b1f5612)

Bug: 1192552
Change-Id: I9fca35ff32e7037c6492f4cee7069e272059b920
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2804382
Auto-Submit: Wez <wez@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#869603}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2826321
Cr-Commit-Position: refs/branch-heads/4430@{#1291}
Cr-Branched-From: e5ce7dc4f7518237b3d9bb93cccca35d25216cbe-refs/heads/master@{#857950}

diff --git a/ui/views/win/hwnd_message_handler.cc b/ui/views/win/hwnd_message_handler.cc
index a23108d0a38af3388b35bd5a0ae3cc3d5e565d93..1332f9ef132b7e5f099cd44f8a4b4831e10dd497 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -1677,7 +1677,13 @@ void HWNDMessageHandler::OnDisplayChange(UINT bits_per_pixel,
                                          const gfx::Size& screen_size) {
   TRACE_EVENT0("ui", "HWNDMessageHandler::OnDisplayChange");
 
+  base::WeakPtr<HWNDMessageHandler> ref(msg_handler_weak_factory_.GetWeakPtr());
   delegate_->HandleDisplayChange();
+
+  // HandleDisplayChange() may result in |this| being deleted.
+  if (!ref)
+    return;
+
   // Force a WM_NCCALCSIZE to occur to ensure that we handle auto hide
   // taskbars correctly.
   SendFrameChanged();